Con­trolling for envir­on­ment­al factors and the tend­ency of birds of a feath­er to flock togeth­er [â€¦] Chris­ta­kis and Fowl­er found that we really do emu­late those we care about, wheth­er we mean to or not. Being con­nec­ted to a happy per­son, for instance, makes you 15 per­cent more likely to be happy your­self. “And the spread of hap­pi­ness does­n’t stop there,” they note. It radi­ates out for three degrees of sep­ar­a­tion, so that, say, your sis­ter­’s best friend’s hus­band’s mood exerts a great­er influ­ence on your per­son­al hap­pi­ness than an extra $10,000 in income would. If he gains 50 pounds, it will be that much harder for you to stay slim, as the frame of ref­er­ence for whatâ€™s “nor­mal” changes through your net­work. Or, on the pos­it­ive side, if he quits smoking, your chances of kick­ing the habit improve, too, even if youâ€™ve nev­er met him. [â€¦]

Pub­lic health work­ers can more effect­ively stop the spread of sexu­ally trans­mit­ted dis­eases if they know what kind of net­work they’re deal­ing with: a hub and spoke (e.g., a pros­ti­tute with many cli­ents) or a more trans­it­ive “ring” net­work where people have few part­ners, but many of these part­ners over­lap (which could hap­pen at a small high school). On anoth­er front, they point out that vot­ing makes little sense for an individualâ€”one vote nev­er decides an electionâ€”but is far more ration­al in a net­work con­text. As with hap­pi­ness and obesity, the decision to vote has reper­cus­sions through three degrees of con­nec­tions. [â€¦] Since lib­er­als and con­ser­vat­ives tend to form their own social net­works, this means that your decision to vote can increase the like­li­hood of hun­dreds of oth­er people vot­ing for the same can­did­ate.

I do won­der if these degrees of sep­ar­a­tion that exert influ­ence on us fluc­tu­ate with the size of each ‘degree’?